Channel-type electric induction furnaces have been used to refine liquid metal melts prior to their being cast.
One example is the use of such a furnace as a converter, into which a steel melt is charged for desulfurization, powdered lime being injected into the melt. The furnace may be of the tilting type, the refining action being effected while the furnace is upright, after which the furnace is tilted and the refined melt poured for casting.
Such a furnace may have a gas-tight cover which is applied after charging, it may be provided with means for injecting non-oxidizing gas into its interior, both before and after charging, and it may have a tap hole which is opened after the furnace is tilted and through which the refined melt may be tapped, the tilting of the furnace to a diagonal position positioning the melt for such tapping.
This expedient has had various disadvantages. The usual tipping channel-type induction furnace is not especially designed to be used as a converter. Its production rate is undesirably low. The temperature of the melt cannot be controlled easily during tapping and it is difficult to maintain a constant pouring or tapping rate. The result is that it is very difficult to obtain high-quality castings.